When Chris Bolgiano needed proof of the devastation from logging years ago in the national forests, she learned quickly where to find it.

The U.S. Forest Service's Photo Collection.

Housed on the 14th floor of the National Agricultural Library in Beltsville, the collection is a kind of photographic memoir of national forests and the people who have inhabited them.

With about 60,000 photographs, it is the largest collection of forestry photographs in the world and gives researchers clues to how Americans moved west, built homesteads and carved a living from the wilderness.

It is here that one might find photos of an eclectic collection of trees, mountains, cabins and flinty-eyed homesteaders, trappers, farmers, miners, loggers and moonshiners.

Susan Fugate, head of special collections for the library, said researchers use the collection to study the cycle of a forest's life and gather information about how homesteaders built their homes, what tools they used and what they wore.

"It was the only place I could turn to for what I needed," said Bolgiano, a Virginia writer researching a book about the history of the national forests between Northern Virginia and southern Georgia.

Bolgiano said she began her book after becoming interested in the history of George Washington National Forest near her home outside Harrisonburg, Va.

She learned quickly that she had better check the photo collection because many of the photos in other forestry books and publications had come from there.

The photos proved to be a treasure of information on how the forests have fared over the years, she said.

"I needed landscape pictures to show the devastation of the forests from all the logging that was going on in the 1920s and '30s and '40s," she said. "I knew they'd have it and they did."

The collection was started in 1898, when Gifford Pinchot, the first chief of the U.S. Forest Service and an avid photographer, ordered his foresters to begin taking photographs of their activities.

If a picture is worth a thousand words, tomes of history are filed in the metal cabinets where the pictures are stored. Most are black and white, with some glossy and some faded to sepia.

The photos include images of loggers in California toppling redwoods with handsaws, rangers using mules to haul water to Arkansas forest fires, and moonshiners brandishing rifles and striking a challenging pose in Tennessee's Cherokee National Forest.

Other photos capture a fire tower observer using a mirror to flash signals and Forest Service "smoke jumpers" training to parachute into forest fires to help extinguish them.

Celebrities play a role in the collection.

Theodore Roosevelt stands in one photo with conservationist John Muir and six other men in front of a Yosemite redwood that dwarfs them. Franklin Delano Roosevelt eats dinner at an Army training camp, and one shot shows the original Smokey Bear, a cub that survived a New Mexico forest fire in the 1940s and became a national symbol of Forest Service fire prevention efforts.

Sara Lee, a special collections librarian, said she gets calls from about two researchers a week seeking access to the collection.

The low number of requests is deceptive, Lee said, because many researchers will end up looking at hundreds of photographs.

"A lot of times, they'll come planning to spend two or three hours and end up spending two to three days here," she said.

Fugate said researchers usually focus on details in photos that are not available elsewhere.

As an example, she noted the details provided by two photos from the collection.

One shot captioned "Mountain farmer and cabin," shows a rugged, bearded mountain man in a 100-year-old wooden cabin in Knox County, Ky. Taken in 1934, the caption reads "Oldest Cabin in Knox County."

Another photo taken in 1907 by an anonymous forest ranger shows a family of "trappers" standing outside a shack in the Florida Everglades.

The photo not only shows what the homesteaders wore and how they lived, but its caption notes that the modest one-story house is made of materials from the surrounding countryside -- cypress bark and palmetto leaves.

The collection is open to the public, but visitors are asked to call ahead at 301-504-5876. Copies of photos are available for a fee.